Power Query 子层次结构 [英] Power Query Child hierarcy

问题描述

我有一个问题需要在电源查询中解决.

I have a problem I need to solve in power query.

我有包含名称、ID 和父 ID 列的表

I have table containing columns Name, ID and Parent ID

Name ID Parent
A    1   
B    2   1
C    3   1
D    4   2
E    5   2

我需要转换此表，以便为该行的每个子项(和原始)获得一行.在本例中，这将产生 11 行.

I need to transform this table so that I get one row for each child (and orginal) that row has. In this example this would yield 11 rows.

Name  ID
A     1
A     2
A     3
A     4
A     5
B     2
B     4
B     5
C     3
etc.

我知道这是通过某种连接完成的，但感觉就像一个循环，我不知道如何在 Power Query 中执行循环.

I know this is done with some sort of joining but it feels like a loop and I don't know how to do loops in Power Query.

推荐答案

试试这个，不一定对，请查一下.有没有人有更好的解决方案?

Try this,not necessarily right,please check it.Does anyone else have a better solution?

let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    Top = Table.SelectRows(Source, each ([Parent] = null)),
    Path = Table.AddColumn(Top, "Path", each #table({"Name","ID"},{{[Name],[ID]}})),
    Loop = Table.Combine(List.Generate(()=>
             Path,     
             each not Table.IsEmpty(_),
             each [ 
                  a = Table.NestedJoin(Source,{"Parent"},_,{"ID"},"join",JoinKind.Inner),
                  b = Table.ExpandTableColumn(a, "join", {"Path"}, {"Pre_Path"}),
                  c = Table.AddColumn(b,"Path", each [Pre_Path]&Table.Group([Pre_Path],"Name",{"ID",(x)=>[ID]})&#table({"Name","ID"},{{[Name],[ID]}}))
                  ][c]
     )),
    Result = Table.Distinct(Table.Combine(Loop[Path])),
    Sort = Table.Buffer(Table.Sort(Result,{{"Name",0}, {"ID",0}}))
in
    Sort

Power Pivot 简单多了，你可以用PATH 来解决Parent-Child Hierarchy 的问题.

Power Pivot is much easier,you can use PATH to solve the problem of Parent-Child Hierarchy.

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